Punching mechanism



Jan. 25, 1938.

J D. BAKER PUNCHING 'MECHANISM Filed NOV. 22, 1935 illllli.,.-|||||1|||||I-l x QN Mw. @Nm .5@

Patented Jan. 25, 1938 UNTED STATES i 2,106,160 PUNCHING MEcHA'NIs'M`lob D. Baker, Gilbertville, Mass'.,as'signor to Su'llivan MachineryCompany, a corporationgof Massachusetts Application November 22, 1933,Serial'No\699',211

28 Claims.

This invention relates to punching mechanisms, and more particularly topunching mechanisms of the pressure fluid actuated percussive type foropening o-r pinning outthe h'oles in hollow vrock drill steel during'theforging operation.

An object of this invention isito provide an improved punchingmechanism; Another object is to provide an improved punching mechanismof the pressure uid actuated'percussive type for opening the holeslinfhollow rock drill steels during-the forging operation. A furtherobject is to provide an improved punching mechanism wherein thepinning.' out tool is'hammeredinto and released from the rock drillsteels-inanimproved manner. Yet another object 1s to provide an improvedvalve controlr mechanism for the hammer motor of such a punchingmechanism. These and other objects will, however,hereinafter more fullyappear.

In the accompanying'drawing therefis shown, for purposes ofillustration, one form.which the invention may assume in practice.

In this drawing.-

Fig. 1 is a longitudinal vertical sectionalv view fr) through theillustrative form of :the improved punching mechanism, the hammeringmechanism thereof shown in pinning-in position.

Fig. 2 is a view similar to Fig. l, showng the hammering mechanism inpinning-out position.

'so Fig.' 3 is a view'similar to Figs. l and 2; showing the hammeringmechanism in'its inoperativel or shut-down position.

In this illustrative embodiment of the invention, there is shown apunching mechanism'gen- "D erally'designatedA I, generally comprisingaiiuid actuated vhammering mechanism 2 #supported on a suitablesupporting frame 3i The hammering mechanism', as shownin` the M drawing,comprises a pressure uid actuated hammer motorhaving a motorcylinderlI'containing a reciprocable hammer piston 5. This hammer pistonis provided with a^forwardly projecting striking bar 6 for transmittinghammer 4,) blows to the shank I of a usual collared pinningout tool orpunch pin 8. This pin .shank is supportedvwithin a chuck 9 carriedwithin` the front part of the motor cylinder. Thexpunch pin collar isindicated at ID. Secured to the rear end of n the motor cylinder is arear head member I I', a valve chest member I2 and a rear head block I3,these parts being held in assembled relation with respect'to thecylinder in any suitable manner. The rear head block is cylindrical inform and is 3.) guided for reciprocatory movement in a concave recess or'guideway Id'formed `on the supporting frame -3,` the-forward end ofthemotor cylinder being guided atv I o-n the supportingframe, As shown, the`supporting .frame has upstanding arms I5A straddling the motor cylinderand .supporting-a releasable pin II.for.h 'ilding` thehammermechanismwithin itsguideson the supporting frame. The rearendwall'I oftherear guide IAOrmS-anlabutment or rear stop for' limiting rearwardmovement of the hammercontrol mechanism,4 while a yoke-.shaped abutmentI9 forms a. front4 stop for, limiting forward movement of. thet hammercontrol -mechanism, the punchfpin `of the hammer-mechanism projectingforwardly through-a vertical sloty 2-9 formed in this yoke. The yoke-fI9 -alsoforms a retainer for precluding -forward release of the punchpinfrom its'chuck.

Theha-mmer motor is Lpreferably of la standard type; and thev valvevmechanism thereof tforI distributing pressure fluidto theemotorcylinderto effect rapidreciprocation of the hammer piston comprisesa "usual yautomatic fluid distributing valver2l "gu-idedffor reciprocatoryymovement in a'bore 22 formedin the valve chest member yI2andf-controllingthe supply of motive fluid owing through-afpassage-23-tothe motor cylinder andV the exhaust `fof iluidfrom the lmotor cylinderthrough aiusualexhaust passage 24. Attached to-therearfhead block I3is-arluid supplypipe 25v` projecting downwardly Ythrough --a slot 26formed rin the `guide portion ofthe `supporting frame, and this'lpipeengageable with the slot ends limits movement 'of the hammeringmechanism in its gu'ides. A passage 21 connects this supply lpipe with alongitudinally extendin g Y axial valve bore`28 formed in the head blockI3. Reciprocable in this/bore 28- is athrottle valve 29 having a groove30 for'connecting the supplypassage ZI'with the supply passage 23.A-.passage 3| connects the supply passage-21 with the bore y 28Aat'f'the `forwardsideof the throttle valve `29 so that the throttlevalve is constantly urged vtoward lits rearmost closed position.

'I'he improved means for controlling the throttle valve 29 for'holdingthe latter open :during for- Ward movement of 'thehammer mechanism 'sothat operation 'of the hammer piston is'eiected during withdrawal orretractive movement of the drill steel, hereinv comprises a valvecontrol member, herein inthe form of ak yoke-shaped member y 33 guidedbetween the arms I6 and having a' longitudinal portion 34 overlying thehammer moto-r and downwardly bent front and rear ends 35 and 36. Therearend 36 of this'V yoke member extends downwardly-between the rearend ofthe head block I 3 and the rear abutment I8, and has a circular recess3l for receiving the rear end of the throttle valve 29, while theforward end 35 of the yoke member is provided with an opening 38 throughwhich the punch pin loosely projects and arranged between the front endof the motor and the front abutment I9.

'Ihe operation of the improved punch mechanism will be clearly apparentfrom the description given. During the forging of the cutting end of thedrill steel S, the central hole therein is wholly or partially closed,and to open up or pin out this hole the drill steel S is placed in theposition shown in Fig. 1 against the forward end of the punch pin 8. Thedrill steel is then moved inwardly toward the hammer mechanism, therebyshoving the punch pin rearwardly, and as a result, the hammer mechanismis moved bodily rearwardly in its guides relative to the supportingframe, to the position shown in Fig. 1. At this time the rear end 36 ofthe yoke member 33 is held against the rear abutment I8 with thethrottle valve 29 held in abutting relation with the bottom of therecess 3'I by the action of the pressure fluid acting on the forwardarea of the valve, and as the hammer motor was moved rearwardly in itsguides the passages 21 and 23 were moved into a position wherein thegroove 30 in the throttle valve connects the same, and as a resultpressure uid is admitted to the motor cylinder to effect reciprocationof the hammer piston. Upon further rearward movement of the drill steel,the punch pin is driven into the drill steel bore. When the drill steelS is pulled rearwardly to withdraw the steel from the punch mechanismand the punch pin is stuck within the steel bore, the punch pin ispulled outwardly relative to the motor cylinder, thereby bringing thecollar I9 thereon into engagement with the front end 35 of the yokemember 33, thereby moving the hammermechanism into the position shown inFig. 2, with the throttle valve 29 held in its open position by the yokemember, and as a result, as the hammer mechanism is moved forwardly thepunch pin 8 is loosened or freed from the drill steel bore. It will thusbe seen that the operation of the hammer is continued during re tractionof the drill steel, and the hammering action thereof on the pin 8effects release of the latter from the steel bore. When the punch pin isfreed from the steel, the yoke member 33 is free to move rearwardly torelease the throttle valve, and the pressure fluid acting on the forwardnd of the throttle valve quickly moves the latter nto its rearrnostclosed position, as shown in Fig. 3; and as a result, action of thehammer motor stops. The forward pin freeing movement of the hammermechanism is a rapid operation, and quick pin release is frequentlyeffected by but a single ham-,mer blow on the punch pin shank, thehammer mechanism jumping back upon engagement with the front abutment Is with a sort of repercussion and the hammer thereof immediatelystopping before the hammer can strike the front end of the valve controlyoke 33 when the latter has moved away from the front abutment I9. Itwill thus be seen that the control Valve 29 is maintained open byengagement with the rear abutment I8 during the hammering-in operationand by the yoke 33, which is distinct from the rear abutment I8, duringthe hammering-out operation.

Under actual operating conditions, the improved punch mechanism has beenfound to be highly effective in opening orfpinning out the holes in rockdrill steels and for releasing a stuck pin from the steel bore, theretractive hammering action effectively freeing a stuck pin from thesteel bore. Moreover, it will be noted that the improved punch mechanismis of an extremely simple and rugged construction which may bemanufactured and kept in repair at a minimum of expense. These and otheruses and advantages of the improved punch mechanism will be clearlyapparent tothose skilled in the art.

While I have in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform is shown for purposes of illustration and that the invention may bemodied and embodied in various other forms without departing from itsspirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a punching mechanism, a uid actuated hammer motor, a Valve forcontrolling the supply of motive fluid to said motor, a pinning out toolactuated by said motor, and means actuated by movement of the pinningout tool relative to the motor and operatively connected to said valveindependently of said motor for controlling said valve.

2. In a punching mechanism, a supporting frame, a hammer motor guidedfor longitudinal movement forwardly and rearwardly along said frame, apunch pin percussively actuated by said hammer motor and to whichpressure is adapted to1be applied by engagement of the work therewithfor controlling movement of said hammer motor forwardly and rearwardlyalong said frame, and means embodying means associated with said punchpin for controlling actuation of said hammer motor, movement of saidhammer motor into its rearward position by application of a rearwardpressure by the work on the punch pin causing said control means toeffect motor actuation to drive percussively the punch pin into thework, and movement of said hammer motor into its forward position byapplication of, a forward pressure by the work on the punch pin causingsaid control means toeffect motor actuation to release percussively thepunch pin from the work. p

3. 'In a punching mechanism, a frame having guiding means, a hammeringmechanism 'guided for back and forth movement in said guiding means, apunch pin percussively actuated by said hammer mechanism and againstwhich pressure is adapted to be applied by engagement of the worktherewith for controlling movement of said hammering mechanism back andforth in said guiding means, and means for causing said hammeringmechanism to operate to effect hammering of the punch pin when saidhammer mechanism is in either its rearward or forward position relativeto said frame guiding means.

4. In a punching mechanism, a uid actuated hammer motor, a valve forcontrolling the supply of motive fluid to said motor, a pinning out toolactuated by said motor, and means actuated by movement of the pinningout tool relative to the motor for controlling said valve and includinga yoke-shaped member extending along one side of the hammer motor andengageable with the pinning out tool and said controlling valve.

5. In a punching mechanism, a fluid actuated hammer motor, a valvecarried within the rear end of the hammer motor for controlling thesupply of motive fluid to said motor, a pinning out tool carried withinthe forward end of the hammer motor and actuated therebyandm'ean'sactuated by' movement ofthe jpinningfouttol relative to the hammermotorfor controlling-*said valve and including'a'memberextending'fa'long one side of the'hammer'motor and engageableat its rearend 'with'said valveandfatf'its'forward end with said pinning out tool;

6. In a punchingmech'anism, a fluidactu'ated hammer motor, a Valvecarried within-the'rear end ofthe hammer motor for controllingU thesupply of motive fluid to said motorya pinning out tool carried withinthe "forwardiend of the hammer motor and actuatedv thereby; and mea-nsactuated by movement v'of thepinning'but'tool relative to thehammerimotorfor controlling said valve and including amemberexter'fdi'vn'gl along one side of thehammer motorandengage'- able at itsrear end with"said"va1veand at"` its forward end with saidpinning 'outtool, the"forward end of said member having 'an-"opening through whichsaid pinning out`tool"projects.l

'7. In a punching mechanismya ksupporting frame having front andrear-abutments andguiding means arranged between saidiab'utm'ents, ahammer motor. guided'for endwiseeciprocatory movement in said guidingmeans relativeto'said frame and between said abutments,-a"valvecar-Aried Within the rear end of the hammer motor forcent-rolling theactuationthereof, a-pinning out tool supported within the'forwardend ofthe hammer motor for actuation therebyfsaidfpinning out tool havingl acollar thereon, and means for controlling said valve by movement of thepinning out tool -relative'to the hammer motor including a yoke-shapedmember extending along one side of the hammer motor andhavinga front endportion extending between lthe` pin collar and the front abutment'andarear portion extending between the 'rear abutment andthe valve.

'8. In a punching mechanism, a supporting frame having front 'andrearabutments 'andguiding means arranged between said abutments,"a hammermotor guided for endwise reciprcatory movement in said guiding meansrelative'to-said frame and between said abutments,y avalvecarried withinthe rear end vofthe lhammer motor for controlling. the actuationthereof; a pinning out tool supported within the forward end of thehammer motor for actuation'thereby; saidpinning out tool having a`collar thereon,'meansf.or controlling said valveby movementiofthepnning out tool relative to the hammer motor "including a yoke-shapedmember extending 'along one side of the hammer motor. and havingia`front end portion extending between'thepin collar 'and the frontabutment and a rear portion extending between the rear abutment andthevalve; said Leinher maintaining said valve in open position duringforward movement of thehammer motor in its guides, and means foreffecting automatic closing of the valve when thepunch'pinis released.

9. In a punch mechanism, a support having a longitudinally extending-guideway, a hammer mechanism slidably guided 'in said guide'way; apinning out tool actuated by said hammermechanism, a valve opened byrearwardlongitudinal movement of said hammer mechanism' in said guidewayfor effecting actuation' of 'said'hammer mechanism to actuatepercussively `saidpinning out tool to drive the latter into the work,and means for maintaining said valve open during forward longitudinalmovement of said hammer mechanism in its guideway'toeffect' actuation ofsaid hammer mechanismto actuate percussively sa-idfpinning-out1too1k torelease the latter from the Work.'r

10?Inianipun'ch-mechanism, a support having mechanism to vactuatepercussively said pinningv out -tool to vdrive`` the latter into thework, and means" forA maintaining said valve yopen during forwardlongitud-inalmovement of said hammer mechanism to actuate percussivelysaid pinning outitool'tofrelease th'elatter from the workysaidlatter-'means including'- means operatively connected to said-valve andsaid pinning out tool.`

11. In a=punchV4 mechanism, a supporthaving a-longitudinally extendingguideway, a hammer mechanism'v slidablyl guided in said `guideway,v apinning out toolactuated by said hammer mechanism,1a'-valve opened'byrearward llongitudinal movement ofsaidfhammer mechanism in saidguidewayfor effecting-actuation of said hammer mechanismtoactua-tefpercussively said pinning outtoolto drive'the latterinto thework, and means'for maintaining' said -valve open during forward@longitudinal movement of said hammer mechanism in its guideway to eiectactuation of said'hammer mechanism to actuate percussively said`pinning-out rtool to releasethe latter from the work,y said meanscomprising an; element extendingv between said pinninglout tool and saidvalve and engaging thelatter for maintaining said valve open during saidforward longitudinal movement.

v'12.11'1 -a'f-punch-V mechanism, the combination of 4a cylinder `havingapiston chamber and a hammer 'pistonin saidlpiston'rchamber, a workingimplement having-a shank provided with a rear impact surface randadaptedfto be actuated percussivelybyfsaid hammer piston, means foreffecting Va'ctiiation of 'said hammer piston'to drive, bythe directhammering -action of the hammer piston on lthe rear impact surface onthe rear end of thefworking-'member shank, said working implementintothe work, and means associated withy andfactuated by movement ofsaid working implement with respect to -said cylinder to eiieciactuation'of saidhammer-piston to release, by the ldirectl'hammering'faction' of the hammer piston on the rear impact surface onthe rear end of the working implement shank, said working implement fromthe work.

13-.Y`In -a punch mechanism, a support having a'guidewaya'hammermechanism guided on said guideway and'comprisinga cylinder having apiston -chamberand apist'on reciprocable in said chamber,v a punch pinactuated by said hammer mechanism, a valve mechanism operatedl bymovement of said hammer mechanism in a rearwarddirection"alongitsguide'way to effect actuation ofthe hammerpiston to` drive the punch pinintothe work, and means associated with and actuatedby said punch pinfor holdingsaid valve mechanism open during forward movement of thehammer mechanism along its guideway to cause-said hammer mechanism toeffect release of the punch pin from the work.

14. `In a'punch mechanism, asupport having a guideway, a hammermechanism -guided on said guideway'andfcomprising'acylinder having apistonch'amberl and a piston reciprocable 'in said chamber, aipunchepinactuatedby saidhammer mechanism, a valve mechanism operated by movementof said hammer mechanism in a rearward direction along its guideway toeffect actuation of the hammer piston to drive the punch pin into thework, and means associated with and actuated by said punch pin forholding said valve mechanism open during forward movement of the workingmechanism along its guideway to cause said hammer mechanism to effectrelease of the punch pin from the work, said latter means including amember engageable with the punch pin and operatively connected to thevalve mechanism for holding the latter open during such forward movementof said hammer mechanism along its guideway.

15. In a punch mechanism, a support having a guideway and end abutments,the forward abutment having an opening, a hammer mechanism slidably-guided on said guideway between said abutments, a collared punch pinactuated by said hammer mechanism and projecting through the opening inthe forward abutment, a valve mechanism operated by movement of saidhammer mechanism in a rearward direction along said guideway to effectactuation of the hammer mechanism to drive the punch pin into the work,and means, including a member having an opening through which the punchpin projects and engageable by the pin collar and extending into aposition with a portion thereof interposed between the rear abutment andsaid valve mechanism, for operating said valve mechanism during forwardmovement of the hammer mechanism' along its guideway to cause saidhammer mechanism to effect release of the punch pin from the work.

16. In a punching mechanism, a supporting frame having front and rearabutments and guiding means arranged between said abutments, a hammermotor guided for endwise reciproca-V tory movement in said guiding meansrelative to said frame and between said abutments, a valve carriedwithin the rear end of the hammer motor for controlling the actuationthereof, a pinning out tool supported within the forward end of thehammer motor for actuation thereby, said pinning out tool having acollar thereon, and means for controlling said. valve by movement of thepinning out tool relative to the hammer motor including a valvecontrolling member extending along one side of the hammer motor andhaving a front end portion extending between the pin collar and thefront abutment and a rear portion extending between the rear abutmentland the valve.

1'7. In a punching mechanism, a supporting' frame having front and rearabutments and guiding means arranged between said abutments, a hammermotor guided for endwise reciprocatory movement in said guiding meansrelative to said frame and between Said abutmentsa valve carried withinthe rear end of the hammer motor for controlling the actuation thereof,a pinning out tool supported within the forward end of the hammer motorfor actuation thereby, said pinning out tool having a collar thereon,means for controlling said valve by movement of the pinning out toolrelative to the hammer motor including a valve controlling memberextending along one side of the hammer motor and having` a front endportion extending between the pin collar and the front abutment and arear portion extending between the rear abutment and the valve, saidmember maintaining said valve in open position during forward movementthe` hammer motor in its guides, and means for effecting automaticclosing of the valve when the punch pin is released.

18. In a punch mechanism, a support having a guideway, a pressure fluidactuated hammer motor slidably guided on said guideway, a punch pinhaving a shank supported in position to receive the impact blows of saidhammer motor, a valve opened by rearward movement of said hammer motorin its guideway to effect actuation of the hammer motor to actuatepercussively the punch pin to drive the punch pin into the work, andmeans for maintaining said valve open during forward movement of thesaid hammer motor in its guideway to effect actuation of the hammermotor to actuate percussively said punch pin shank to loosen the punchpin in the work during such forward movement, said hammer motor having ahammer element for delivering impact blows directly to the punch pinshank during both rearward and forward movements of said hammerA motoralong its guideway.

19. In a punch mechanism, a support having a guideway, a pressure fluidactuated hammer motor slidably guided on said guideway, a punch pinhaving a shank Supported in position to receive the impact blows of saidhammer motor, a valve opened by rearward movement of said hammer motorin its guideway to effect actuation of the hammer motor to actuatepercussively the punch pin to drive the punch pin into the work, andmeans for maintaining said valve open during forward movement of thesaid hammer motor in its guideway to effect actuation of the hammermotor to actuate percussively said punch pin shank to loosen the punchpin in the work during such forward movement, said hammer motor having ahammer element for delivering impactblows directly to the punch pinshank during both rearward and forward movements of said hammer motoralong its guideway, said hammer motor and said latter means movingautomatically into inoperative position to close said valve to shut downthe punch mechanism when the punch pin is released from the work.

20. In a punch mechanism, a hammer motor having an impact element, apunch pin actuated thereby and having a shank provided with a rearimpactV surfacel adapted to receive the impact blows of said impactelement, and means controlled by engagement of the work with the punchpin for effecting actuation of the hammer motor to actuate, by a directhammering action of said impact element on said rear impact surface onthepunch pin shank, the punch pin to drive the latter into the work andto effect release thereof from'the Work.

21. In a punching mechanism, a fluid actuated hammer motor, a Valve forcontrolling the supply of motive fluid to said hammer motor, a pinningout tool actuated by said motor, and means actuated by engagement of thework with said pinning out tool for controlling said valve toeffectmotor actuation thereby to actuate by a hammering action thepinning out tool to drive the latter into the Work and to effect releaseof the tool from the work and including valve operating meansoperatively connected to the valve independently of the motor, saidcontrolling means embodying means for maintaining said valve inoperative position by engagement of the pinning out tool with said lastmentioned means during the release of the pinning tool from the work.

AIn a punch mechanism, the combination of a pressure fluid actuatedhammer motor having a cylinder and a hammer piston in said cylinder, asupporting frame for said hammer motor, a working implement adapted tobe percussively actuated by said hammer piston, means for controllingthe supply of pressure fluid to said hammer motor, means for operatingsai-d control means to effect actuation of said hammer motor to causesaid hammer piston to actuate percussively said working implement in aforward direction for driving the working implement into the work, andmeans associated with and actuated by movement of said working implementwith respect to said cylinder foroperating said control means to effectactuation of said hammer motor to cause said hammer piston to actuatepercussively said working implement in a forward direction for releasingsaid working implement from the work, said control means assumingdifferent positions with respect to said motor support during thedriving in and releasing operations of said hammer motor.

23. In a punching mechanism, a support having a guideway, a hammer motormounted for back and forth movements on said guideway, a punch pinactuated by said hammer motor and to which pressure is adapted to beapplied by the work for controlling movement of said hammer motor intoits rearward and forward positions on said guideway, and control meansfor said motor operative when said motor is in its rearward position toeffect actuation thereof to drive the punch pin into the work andembodying means operative when said motor is in its forward position toeffect actuation of said motor to release the punch pin from` the work,

24. In a punching mechanism, a hammer motor, control means for saidmotor, a punch pin actuated by said hammer motor and to which pressureis adapted to be applied by the work for operating said control means toeffect motor actuation, said punch pin having a shank provided with arear impact surface on its rear end, pressure being applied in arearward direction by the work to the punch pin to operate said controlmeans to effect motor actuation to drive, by the direct impact of thehammer motor on the rear impact surface on the rear end of the punch pinshank, the punch pin into the work, said controlling means embodyingmeans operated by pressure applied to the punch pin by the work in aforward direction to operate said control means to effect motoractuation to release, by the direct impact of the hammer motor on therear impact surface on the r'ear end of the punch pin shank, the punchpin from the work, elements of said control means assuming differentbodily located positions during the driving in and releasing operations.

, and movable relative to said motor for controlling said valve toeffect actuation of said motor to release the pinning out tool from thework.

26. In a punching mechanism, a fluid actuated hammer motor mounted forbodily movement forwardly and rearwardly, a valve for controlling thesupply of motive fluid to said motor, a pinning out tool actuated bysaid motor, means for controlling said valve when said hammer motor isin its rearward position to effect actuation of said pinning out tool,and means embodying means distinct from said controlling means forcontrolling said valve to effect actuation of said pinning out tool whensaid motor is in its forward position, said valve and certain elementsof its controlling means moving bodily with said hammer motor duringmovement of the latter from its rearward position to its forwardposition.

27. In a punch mechanism, a hammer motor having an impact element, apunch pin actuated thereby and having a shank provided with a rearimpact surface on its rear end adapted to receive the impact blows ofsaid impact element, and means controlled by movement of said punch pinselectively in opposite directions by engagement of the work therewithfor effecting actuation of said hammer motor during both directions ofmovement of said punch pin to actuate, by a direct hammering action ofsaid impact element on said rear impact surface on the rear end of thepunch pin shank the punch pin to drive the latter into the work and toeffect release thereof from the work.

28. In a punch mechanism, a hammer motor having an impact element, apunch pin actuated thereby and having a shank provided with a rearimpact surface on its rear end adapted to receive the impact blows ofsaid impact element, means controlled by movement of said punch pin byengagement of the work with said punch pin for effecting actuation ofsaid hammer motor to drive, with a direct hammering action of saidimpact element on said rear impact surface on the rear end of the punchpin shank, the punch pin into the work, and cooperating means controlledby movement of the punch pin in the opposite direction by engagement ofthe work therewith to release, by a direct hammering action of saidimpact element on said impact surface on the rear end of the punch pinshank, the punch pin from the work.

JOB D. BAKER.

CERTIFICATE OF CORRECTION. Patent No.. 2,106,160. January 25, 1,938.

JOB D. BAKER,

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5second column, line LL, claim lO, for "an" read a; page 5, secondcolumn, line 56, claim 28, after the word "said" second occurrenceinsert rear; and that the said Letters Patent should be read'with thesecorrections therein that the same may conform to the record of the casein the Patent Office Signed and sealed this lst day lof March, A, l D,19%8 Henry Van Arsdale, (Seal) Acting Commissioner of Patents.,

